Standing in a cinderblock auto body shop in Mattapan, Republican Senate candidate Gabriel E. Gomez blasted his Democratic opponent, US Representative Edward J. Markey, for voting to raise taxes 271 times during his 36 years in Congress.

“He’s raised taxes on everything from gas to a pint of Sam Adams beer,” Gomez declared.

The tax attack was the latest salvo from a candidate who has bounced from criticism to criticism as he challenges Markey in the race for US Senate.

While some say the rotating messages are a sign of a campaign that is methodically rolling out attacks, others say Gomez is frantically searching for a message that will resonate with voters before the June 25 election.